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81.
Increasing K+ adsorption can be an effective alternative in building an available K pool in soils to optimize crop recovery and minimize losses into the environment. We hypothesized that long-term fertilization might change K+ adsorption because of changes in the chemical and mineralogical properties of a rice (Oryza sativa L.). The aims of this study were (i) to determine clay minerals in paddy soil clay size fractions using X-ray diffraction methods and a numerical diagram-decomposition method; (ii) to measure K+ adsorption isotherms before and after H2O2 oxidation of organic matter, and (iii) to investigate whether K+ adsorption is correlated with changes in soil chemical and mineral properties. The 30-yr long-term fertilization treatments caused little change in soil organic C (SOC) but a large variation in soil mineral composition. The whole-clay fraction (<5 μm) corresponded more to the fertilization treatment than the fine-clay fraction (<1 μm) in terms of percentage of illite peak area. The total percentage of vermiculite-chlorite peak area was significantly negatively correlated with the total percentage of illite peak area in the <5 μm soil particles (R=-0.946, P<0.0006). Different fertilization treatments gave significantly different results in K+ adsorption. The SOC oxidation test showed positive effects of SOC on K+ adsorption at lower K+ concentration (?120 mg L?1) and negative effects at higher K+ concentration (240 mg L?1). The K+ adsorption by soil clay minerals after SOC oxidization accounted for 60–158% of that by unoxidized soils, suggesting a more important role of soil minerals than SOC on K+ adsorption. The K+ adsorption potential was significantly correlated to the amount of poorly crystallized illite present (R=0.879, P=0.012). The availability of adsorbed K+ for plant growth needs further study. 相似文献
82.
Soil Chemical Properties and Nutrient Composition of Cocoyam Grown in an Organically Fertilized Soil
《Communications in Soil Science and Plant Analysis》2012,43(16):1955-1965
ABSTRACTField experiments were conducted for two consecutive years to evaluate the influence of cow dung and rice husk application rates on soil chemical properties and nutrient composition of cocoyam cormels. The treatments comprised four rates each of cow dung and rice husk (0, 10, 20, and 30 t/ha) arranged as a factorial experiment using randomized complete block design with three replicates. The treatments were incorporated into the soil 2 weeks before planting of cocoyam each year. After 2 years of cropping, soil samples were collected from the respective plots and analyzed so also cocoyam cormels. Cow dung application positively and significantly (P < .05) affected soil pH, organic matter (OM), and the soil nutrients (r = 0.95, 0.98, and 0.94–1.00, respectively) while rice husk application significantly and positively influenced soil OM, nitrogen and phosphorus (r = 0.98, 0.95, and 0.98, respectively). Aside potassium content that was enhanced, cow dung application did not significantly affect the nutrient composition of the cocoyam cormels. However, 30 t/ha of applied rice husk caused significant reduction in crude protein and fiber contents but significant increase in carbohydrate. There was negative and significant correlation between rice husk and the cormels crude protein (r = ?0.97). A total of 20 t/ha each of the organic fertilizers was found to be optimum for improving soil fertility and invariably yield without compromising the nutrient content of the cocoyam cormels. 相似文献
83.
抚顺西排土场矸石山阴坡随着排矸年限的增加,物种多样性发生变化,物种数由初期的4科5种增至后期14科29种。植被由最初的鹅绒藤+豚草+刺蒺藜群落,逐步演变到榆树群落。在阴坡,不同排矸年限的样地,植物群落多样性指数随着排矸时间的延长而增加;物种综合多样性指数、丰富度指数与排矸年限呈显著正相关关系。 相似文献
84.
《Communications in Soil Science and Plant Analysis》2012,43(6):707-716
Abstract Details and some evaluation are given of the use of a dialysis method for sampling pore water from depth in wetland substrata (peats), with particular reference to measurement of concentrations of ion species with stabilities dependent on redox potential. The method is based upon the burial and subsequent retrieval (after equilibration) of cells made from dialysis membrane filled with deionized water. Preliminary results of field investigations of concentrations of dissolved iron and sulphide in the pore water of base‐rich mires, as sampled by this method, are given. Results suggest that the method could have very considerable application and that its potential, and possible problems, deserve further examination. 相似文献
85.
The results showed that the essential oil from Piper sarmentosum has strong antifeedant and toxicity effects on Brontispa longissima. The best antifeedant and contact toxicity effects were observed in the 1st-2nd instar larvae. The essential oil also displayed a notable fumigation effect on the eggs and pupae of B. longissima. It took the control-treated insects 43.34 d to complete one generation, while the insects treated with 2000 mg/L essential oil needed 73.58 d. The essential oil was analyzed by gas chromatography/mass spectrometry and 41 components were identified. Myristicin (65.22%) and trans-caryophyllene (13.89%) were the major components. Myristicin exhibited strong antifeedant and contact toxicity effects on both the 3rd instar larvae and the imagoes of B. longissima, when it showed a significant fumigation effect on the eggs and pupae of B. longissima. Another P. sarmentosum essential oil and myristicin all showed a strong inhibiting effect on the growth and development of B. longissima along with the activity of AChE, CarE, GSTs and Na+, K+-ATPase in B. longissima larvae. 相似文献
86.
为验证链烷技术测定蝗虫食性的精确性,确定蝗虫粪便中链烷的回收率。于2007年夏季在内蒙古太仆寺旗天然草地,用优势植物羊草(Leymus chinensis)、糙隐子草(Cleistegenes squarrosa)和克氏针茅(Stipa kylovii)各500g,饲喂360只成虫的亚洲小车蝗(Oedaleus asiaticus)。试验期内每天记录蝗虫实际牧草采食量、采食成分和排粪量,利用气相色谱分析牧草和粪样的链烷含量,应用链烷技术测定蝗虫的牧草采食比例,并与实际值进行比较。结果表明,3种牧草链烷模式存在种间差异;蝗虫粪便中链烷的回收率随链烷长度的增加而线性增加;蝗虫采食羊草、糙隐子草和克氏针茅比例的测定值与实际值存在显著正相关(P<0.05),相关系数分别为0.925 5、0.956 6和0.978 2。因此链烷技术可以精确测定典型草原蝗虫的食物组成。 相似文献
87.
Palm press fibre (PPF) was obtained from two sources, a small-scale oil palm processing unit and a large-scale factory processing unit, and its chemical composition was determined. In vitro digestibility techniques were used to assess the feeding value of untreated, defatted and sodium hydroxide-treated PPF. For the NaOH treatment, 0.5 g oven-dried PPF was treated for 24 h with 5% NaOH in three ways: treated and not washed (NaNW); treated and washed (NaW); and treated after milling (NAD).The results indicate that, on a dry matter basis, PPF is low in nitrogen (12–13 g/kg), moisture (37–90 g/kg) and ash (53–62 g/kg), but high in ether extract (269–355 g/kg), neutral detergent fibre (532–768 g/kg), acid detergent fibre (375–548 g/kg) and lignin (219 g/kg). The in vitro dry matter digestibility values were low for the samples from both sources, but the large-scale factory-processed PPF had higher in vitro dry matter digestibility (0.215 vs 0.166) and in vitro organic matter digestibility (0.196 vs 0.145). Defatting the PPF and treating it with 5% NaOH solution significantly (p<0.01) improved both the dry matter and organic matter digestibility. Washing the NaOH-treated PPF resulted in a higher digestibility of dry matter as against NaNW or NAD. These results suggest that defatting and treatment with 5% NaOH would improve the feeding value of PPF. 相似文献
88.
89.
90.
Gengmei?Xing Jun?Zhang Jing?Liu Xiaoyan?Zhang Genxuan?WangEmail author Yafu?Wang 《Phytoparasitica》2003,31(5):499-514
The impacts of elevated CO2 and soil water on the population dynamics, adult fecundity and nymphal period of the bird cherry-oat aphidRhopalsiphum padi (Linnaeus) were evaluated in three experiments: (i)Combined effects of CO
2
and soil water on aphid populations. Spring wheat was grown in pots at three CO2 concentrations (350, 550 and 700 ppm) and three soil water levels (40%, 60% and 80% of field water capacity, FWC) in field
open-top chambers (OTC) and infested with the bird cherry-oat aphid. Aphid population dynamics were recorded throughout the
growing season; at the same time, adult fecundity and duration of the nymphal period were recorded. Chemical composition of
spring wheat leaves was also analyzed. (ii)Indirect effects of CO
2
concentrations and soil water on aphid adult fecundity and nymphal period. The experiment was conducted with the leaf discs method in the laboratory. Aphids were reared on leaf discs excised from
the treated wheat in OTC with different CO2 and soil water levels. (iii)Direct effects of CO
2
concentrations on aphid adult fecundity and nymphal period. Aphids were reared on leaf discs excised from the wheat grown under natural conditions. The experiment was conducted with
the leaf disc method in OTC with the three CO2 concentrations. It was found that the direct effect of CO2 concentration on aphid population parameters was minor. CO2 and soil water affected aphid population indirectly through their effects on wheat characteristics. The aphid population
under 550 ppm CO2 was far larger than the one under 350 ppm CO2, whereas the population under 700 ppm CO2 was slightly higher than that under 550 ppm CO2. The largest aphid population was obtained with the 60% soil water treatment, regardless of CO2 treatment. The effects of CO2 concentration on aphid population were, however, not significantly correlated with soil water level. Adult fecundity increased
with CO2 concentration, the highest fecundity being achieved under 60% FWC treatments. The nymphal period was not affected by CO2 concentration. The shortest period occurred under 60% FWC. Atmospheric CO2 and soil water had significant effects on the chemical composition of the wheat leaves. Aphid population size was positively
correlated with leaf water content, concentrations of soluble proteins, soluble carbohydrates and starch, and negatively correlated
with DIMBOA and tannins concentrations.
http://www.phytoparasitica.org posting Oct. 20, 2003. 相似文献